I think the success has been largely squandered.
Too much focus on divisive balance changes as “content” and a real lack of new maps, new modes and player options outside of refining the restrictions they imposed on Comp.
When Team Fortress 2 was as old as Overwatch is now it had added a really robust PvE mode (MvM) and about twice as many maps. And a far higher proportion of maps in Overwatch are much less impressive Deathmatch-only or CTF-only maps which just don’t work for smaller teams of Overwatch.